Abstract: This paper deals with the method by using quasi observation. In the contribution, a simple algorithm is developed for the adjustment computation with quasi observation at first. And then the ability of the quasi observation to improve the search technique is studied in detail.The results has shown that the quasi observation cannot only strengthen the residual test but also can change the structure of the search space. The robustness of the method is also presented. A method to determine the weight of quasi observation is proposed. At last the field tests are carried out to show that the proposed method is effective.?