Abstract: In order to analyse the performance of suppression nonlinear productions of feedforward amplifiers, the suppression equation of the loop has been established based on the model of a suppression loop. And the function relation between the performance of suppression nonlinear productions and the mismatching of amplitude, phase and delay of the loop has been developed. Simulation and analyzing results show that the delay mismatching is the dominant factor to affect the bandwidth of a feedforward amplifier. The resuts are significant for the design and debugment of the feedforward amplifiers.