The subsea cable ploughs for the cable laying ships are the special equipment for subsea cable laying. Under the towing force provided by the tow line of the cable laying ship, the cable plough can operate cable laying while trenching on the seabed. The stress condition is very complex during the working process of the cable plough. It is necessary to comprehensively analyze and study the force acted on the whole machine and the force of the towing line of the cable playing ship during the operation of the burial plough, in order to maintain the effective excavation of the seabed soil and stability. A deep-water burial plough under excavation condition is examined to analyze the correlation between the force of the burial plough and the towing force of the cable laying ship starting from the forces of the whole burial plough. It can provide theoretical basis for the reasonable selection of the towing line and the parameter determination to ensure the success subsea trenching and the cable laying operation of the cable plough.