In order to study the influence of various factors on the forage crops conditioning performance and improve the quality of forage crops after harvest, a toothed roller conditioning test bench with adjustable space between conditioning rollers was designed. The test bench was mainly composed of conditioning roller, gap adjusting mechanism, quick changing mechanism of conditioning roller and measurement and control system, etc. The measurement and control system can collect the torque and speed information between the fixed roller and the transmission shaft in real time, and then calculate the energy consumption of the test bed. In order to test the performance of the conditioning test bench, taking the rotate speed of the fixed roller, the feeding rate of the per unit working length of the conditioning rollers and the gap of the conditioning rollers as the experimental factors, the unit energy consumption, the stem breakage rate and the grain breakage rate as the target values, a three-factor three-level response surface test with the Box-Behnken test method was carried out using forage crops. By the analysis of the test data, the quadratic regression models of the unit energy consumption, the stem breakage rate and the grain breakage rate were established, respectively, the optimal solution of the working parameters of the forage crops conditioning test bench were achieved, that was, the rotate speed of the fixed roller was 1157r/min, and the feeding rate of the per unit working length of the conditioning rollers was 10.84kg/(m〖DK〗·s), and the gap of conditioning rollers was 2.6mm. Meanwhile, the optimal solutions of the conditioning qualities of the forage crops under the optimal working parameters conditions were achieved, respectively, that was, the unit energy consumption was 2347.44J/kg, the stem breakage rate was 95.66%, and the grain breakage rate was 95.19%. Subsequently, the working parameters of the forage crops conditioning test bench were set as the optimal solution parameters of the models listed above, the confirmation tests with the forage crops were carried out. The results showed that the measurement values of the conditioning quality parameters of the forage crops under the optimal working parameters conditions were consistent with the optimization results, that was, the unit energy consumption, the stem breakage rate and the grain breakage rate of the forage crops were respectively 2377.53J/kg, 95.62% and 95.02%, the relative errors between the solution optimization values of the models and the measured values of the confirmation tests were less than 1%. The research results provided data reference and technical support for the design of forage crop conditioning machinery and the selection of working parameters.