Abstract: In this paper,the correlation analysis of a self-calibrating bundle block adjustment and the test of significance of additional parameters are carried out by the use of a selected orthogonal additional parameter set.The main objects of study are namely:the theoretical accuracy of the adjusted coordinates and the additional parameters,the correlation coefficients among the additional parameters and between the additional parameters and the ground point coordinates,the choice of additional parameters according to the test of significance.All of these studies are performed with different weights of additional parameters.The basic conclussions obtained are:(1) The theoretical accuracy of adjusted coordinates and additional parameters as well as the correlation between additional parameters and ground point coordinates are related to the choice of the weight of additional parameters.(2) Under certain geometrical conditions some additional parameters of an orthogonal parameter set might be highly correlated with ground point coordinates.(3) From the correlation analysis by the use of synthetic data for the given geometric figure of the block and the adopted additional parameter,we can find out those parameters which are very sensitive to their weights or which can not be easily determined exactly or which will bring out high correlations among the unknowns.If those parameters are removed from the equations or are given a bigger weight,the self-calibrating adjustment will be able to obtain a reliable accuracy improvement.In this case,the adjusted results will become insensitive to the weight of additional parameters.(4) Vice versa,if the weight of additional parameters can be correctly determined according to their signal-to-noise ratio,the correlation analysis and the test of significance of additional parameters can he exempted from the adjustment procedure when the imitation errors for systematic errors are not considered.Thus,an efficient accuracy improvement can be expected.At the end of this paper some suggestions are made in accordance with the investigations in[1]、[2]and this paper for the proper use of self-calibration in production work.