Crucian,grass carp,bream and yellow catfish were used to study the stress distribution of carborne live fish in the process of linear acceleration and deceleration.Using the least squares method and Gaussian function as the fitting function,the force value curves of the braking phase when traveling in a straight line of 40,60,80 km/h were respectively fitted,and the particle swarm algorithm was used to optimize the curve after fitting.The final curve had a coefficient of determination between 0.902 and 0.986,and the standard error was between 0.058 and 0.145.The fitting effect was good.The results of analyzing effects of different types of fish and vehicle speed on the fitting curve showed that the greater the speed in straightline driving,the larger the proportional coefficient and peak width parameter of the braking curve of the braking phase.Under the same situation,the squid was most affected by the braking (38.02 N) and the carp was the smallest (15.69 N).The speed of the vehicle and the type of fish in the straight line had no obvious influence on the position parameters,and the speed of the vehicle during straight running had no significant influence on the index of the fitted curve.The results of analyzing the force of the pressure test board in the braking phase showed that the measured value of the pressure in the braking phase was smaller than the theoretical value,and the relative error was less than 15.990%.