Abstract: In order to solve the problem of the optimization of the observed peg-top azimuths position and the adjustment of the direction connecting traverse，in this paper,the theory and simulation analysis method are used to carry out the research on the optimization method and the general model of the adjustment of the underground equilateral straight-extended form of connecting traverse.The main conclusions are as follows：①Based on Lagrange's extreme value method,it is proved that the equal distance is the best form to measure the observed peg-top azimuths，and obtain the law of the position of the observed peg-top azimuths with different types and different orientation accuracy.②Based on the adjustment of the condition observations,this paper establishes the model of the Direction connecting traverse adjustment of the peg-top azimuths，and verifies the correctness of the model with the simulative example of a direction connecting traverse.The results of research have important reference for the optimization of the underground direction connecting traverse connection and data processing.

Key words: Gyro orientation, Direction-connecting traverses, Adjustment model, Holing through survey, Optimal position of additional surveying