When the rock drilling jumbo uses the automatic mode,its boom swing and pitch have coupled motion,which is a difficult problem to solve.Therefore,a cascade PID compound control algorithm for boom coupled motion was proposed.According to the schematic diagram of the mechanical structure of the boom,the reasons for the coupled motion of the boom pitch and swing joints were analyzed.Then,the positional PID and incremental PID were analyzed,which were suitable for the position loop and speed loop control of the cascade PID,respectively.The coupled motion cascade PID compound control algorithm was designed,and the specific calculation process was explained.Finally,the control system was tested on the test platform,the effectiveness of the control algorithm and the stability of the control system were verified.The research results show that the control algorithm can be used to effectively solve the problem of boom coupling motion,and the inner and outer loop coordination of cascade PID makes the control system stable;under the step signal,the overshoot of target angle is small (0.5%),and under the slope signal,the dynamic tracking effect of cylinder motion speed is good,and the maximum fluctuation rate of angle error is 15.87%.