I can do ESC,Accel,and Compass Calibration are all succeed.But can’t test motors and arm.
MP.param (15.4 KB)
Welcome to the community 
Your BATT_LOW_VOLT is set to 6 [V] and your BATT_FS_LOW_ACT is set to 2 meaning RTL.
With a voltage of 4.11V it is below the threshold for triggering the battery-low-failsafe, thus preventing you from arming.
Follow Methodically configure and tune ArduCopter for step-by-step configuration instructions