A new computational formula to nonlinear adjustment by parameters, in consideration of the second-order terms, is derived in this paper from the precise orthogonality condition equations to nonlinear least squares by analyzing the direct solving process and iterative computing method of the linearized model 在分析線性化的非線性參數(shù)平差的近似直接解法與迭代解法基礎上,利用非線性最小二乘的精確正交性條件方程,推導出顧及到二次項的非線性參數(shù)平差的一種新的計算公式。