Currently, master-slave servo position control mode is mostly adopted in underwater manipulators. Due to the low operating precision , it is difficult to meet the requirements of high precision underwater autonomous operation. In order to solve the problem, we proposed an online adjustment programming algorithm in which a force sensor was used to measure the control error of the manipulator end by taking a 7-function underwater electric manipulator as research object. The manipulator end position error of the force sensing online planning was smaller than that of the no-force sensing offline planning , comparing the simulation results under the same controller. By the adjustment of online trajectory planning , the method can effectively reduce the manipulator end position error and adjust the internal force to a small range , which protects the operating target and manipulator effectively.