We should not put scrollable view inside scrollable view (and most developers say we should never put ListView inside ScrollView). But there are cases where we have to put the scrollable view inside Scrollable view inspite of these design guidelines.
When we put a scrollable view(Parent) inside a scrollable view(Child), it locks the touch intercept of the child view as the parent view has more priority over child. Therefore, you can't scroll the child view.

Following is the code to scroll the child view, it locks the touch intercept of parent view when a child view is touched.

Below is the example layout with scrollview inside a scrollview:
activity_main.xml

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:paddingLeft="@dimen/activity_horizontal_margin"
    tools:context=".MainActivity"
    android:background="@android:drawable/alert_dark_frame"
    android:id="@+id/svParent"
    >
<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
   <ImageView
        android:layout_width="wrap_content"
        android:layout_height="1200dp"
        android:src="@android:drawable/sym_def_app_icon"
        android:scaleType="fitXY"
        android:layout_centerInParent="true"/>
<ScrollView
    android:id="@+id/svChild"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:background="@android:drawable/alert_light_frame"
    android:layout_centerInParent="true">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="600dp"
        android:src="@android:drawable/sym_def_app_icon"
        android:scaleType="fitXY"/>
    <LinearLayout>
<ScrollView>
<RelativeLayout>
<ScrollView>

And following is the code to make child view scrollable when user touches it.
MainActivity.class

public class MainActivity extends Activity {
private ScrollView svParent;
private ScrollView svChild;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        svParent = (ScrollView) findViewById(R.id.svParent);
        svChild = (ScrollView) findViewById(R.id.svChild);

        //This is the code to lock the parent touch intercept when 
          child scrollview is touched

        svChild.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                int action = event.getAction();
                switch (action) {
         //When user touch the child view
              case MotionEvent.ACTION_DOWN:
              // Disallow ScrollView to intercept touch events.
             svParent.requestDisallowInterceptTouchEvent(true);
                // Disable touch on transparent view
                      return false;
          //When user releases the touch event
                case MotionEvent.ACTION_UP:
                // Allow ScrollView to intercept touch events.
                  svParent.requestDisallowInterceptTouchEvent(false);
                       return true;
         //Move gesture of the user on the child view
                  case MotionEvent.ACTION_MOVE:
                // Disallow ScrollView to intercept touch events.
                    svParent.requestDisallowInterceptTouchEvent(true);
                     return false;
                    default:
                        return true;
                }
            }
        });
    }
}