In order to acquire the output performance of the balanced doublestator multipump, by studying the effect of the vanes in one acting period on the  flow pulsation of the pump, the mathematic relationship between the vane number and the instantaneous flow rate was obtained. At the same time, the influence of the initial angle on the output characteristics when the inner and the outer pumps work alone was considered. The effect of lag angle on the teamwork of the pumps was also discussed. It turns out that the flow pulsation of the even vane is smaller when the acting number of balanced doublestator multipump is even and is less than or equal to nine vanes in one acting period, however, the flow pulsation of odd vane is smaller, when the acting number of the pump is more than nine. The theoretically foundation was laid for the design of balanced double-stator multi-pump.