Please help me !(APM 3.2 Firmware(stable))

Hi boys:
I use APM 3.2 firmware (stable) on a quadrotor. when I set the flight mode to RTL from Loiter,the quadrotor slowly down frome home positon.But when I control the yaw at this time, the quadrotor clime up suddenly and up to 300m .it is so quickly!!
anyone can help me?
thanks so much.

The appendix is my flight log.