Abstract:The calculation adjustment formulas based on total least squares (TLS) is deduced. In total least squares adjustment(TLSA), the stochastic model is solved by matrix vector operator. Different from the published research, the observations and elements in coefficient matrix are heteroscedastic and correlated. In trilateration net, the known points are obtained from higher grade surveying and adjustment, so the coordinates of these known points have errors. Furthermore, the coefficient matrix of trilateration net’s error equation has errors and is correlated to the observations. Seeing that, the trilateration net total least squares coordinates adjustment is presented. At last, through an example, the method is discussed, and some conclusions are drawn.