Abstract: The joint acquisition algorithm is used for collection detection of the multi-satellite signals, given the lack of analysis and assessment on its detection performance. To make the case, the processing gain is adopted to measure the improved the level of sensitivity of the joint acquisition as opposed to the traditional acquisition; the analytic expressions of the processing gains are given respectively with the ideal assumption and the errors of the signal synchronization parameters; the detection losses caused by the delay and Doppler errors are analyzed in detail; the detection losses of the joint acquisition are compared with those of the traditional acquisition. Furthermore, some simulations are performed to verify the analytic results, which show that most of the detection loss in the joint acquisition is less than those in the traditional one.