In the practical application of the GBAS pseudo-differential position, there had been abnormal Altitude-jump phenomena in the differential positioning process at some time. After some detailed analysis for the real flight-tests data, the primary cause of the problem was the excessive pseudo-range error of the new-locked satellites at this time and it produced the differential correction which had large error. In response to this question, the traditional solution was to prolong the minimum threshold of the receiver lock-in time to fixed 60 seconds, but this method was merely based on practical experience, it was relatively simple and crude, lacked of theoretical basis. The combined anti-error estimation algorithm described in the paper could greatly shorten the convergence time of the receiver pseudo-range and improve the pseudo-range accuracy properly. By applying this algorithm to the preprocessing of the new-locked satellites pseudo-range measurements, then through the follow-up test verification, we ensured this problem had been thoroughly solved.