Abstract: With the popularization of the use of electronic distance measuring equipment and the increase of the accuracy of ranging, three-dimensional terristrial trilateration nets find more and more application in engineering surveying. So far, however, not enough research has been made on the adjustment and accuracy evaluation of the nets. To treat the problem, the present article offers a simple and convenient way for adjustment——adjustment on mechanical principles accompanied by a BASIC program. The advantages and efficiency of this method are tested and verified through numerical examples.