In order to study the working performance of straw baler, this experiment adopts the self-developed test-bed of straw compression and bale. The unit power consumption, piston pressure, connecting rod pull pressure and bale density are obtained through survey and calculation. Then it analysis the influence of the different compression speed and different feeding amounts on machine performance and the components in the constant condition of factors such as straw moisture content. The results show that the best working performance of straw baler occurs when feeding amount is 1.0 kg/s and compression speed is 80 times/min. And the change of compression speed and feeding amount has little effect on bale density.