In order to increase the sensor range and adapt to the large load requirements, based on the 8/4-4 parallel piezoelectric sixaxis force sensor, a sixaxis force sensor with 8/4-4 split-load parallel structure is proposed. Based on the principle of large force distribution, on the basis of 8/4-4 parallel piezoelectric sixaxis force sensor, the piezoelectric ceramics are used as sensitive components for each branch, and a central load beam is added so that it makes the generalized sixaxis force of the most external loads of the sensor widely distribute. The mathematical model of 8/44 splitload parallel six-axis force sensor is established and its decoupling algorithm is deduced. By comparing the ADAMS example simulation with the theoretical model, the mathematical model of the sixaxis force sensor and the decoupling algorithm have an error of less than 0.14%, thus verifying its accuracy.