android:theme="@android:style/Theme.Holo.Light.DialogWhenLarge.NoActionBar"

setDatePickerDividerColor(datePicker);

/** 
 * 设置时间选择器的分割线颜色 
 * 
 * @param datePicker 
 */ 
private void setDatePickerDividerColor(DatePicker datePicker) { 
  // Divider changing: 
 
  // 获取 mSpinners 
  LinearLayout llFirst = (LinearLayout) datePicker.getChildAt(0); 
 
  // 获取 NumberPicker 
  LinearLayout mSpinners = (LinearLayout) llFirst.getChildAt(0); 
  for (int i = 0; i < mSpinners.getChildCount(); i++) { 
    NumberPicker picker = (NumberPicker) mSpinners.getChildAt(i); 
 
    Field[] pickerFields = NumberPicker.class.getDeclaredFields(); 
    for (Field pf : pickerFields) { 
      if (pf.getName().equals("mSelectionDivider")) { 
        pf.setAccessible(true); 
        try { 
          pf.set(picker, new ColorDrawable(Color.parseColor("#cccccc")));//设置分割线颜色 
        } catch (IllegalArgumentException e) { 
          e.printStackTrace(); 
        } catch (Resources.NotFoundException e) { 
          e.printStackTrace(); 
        } catch (IllegalAccessException e) { 
          e.printStackTrace(); 
        } 
        break; 
      } 
    } 
  } 
}