Abstract：The discontinuity in rock mass is assumed as a disc，and the diameter becomes an important parameter of its spatial distribution. The diameter can be deduced from the observed trace length. A new trial algorithm for diameter was proposed，which simulated discontinuity distribution with Monte Carlo method，deduced distribution relation with analytic geometry and programmed with Excel or C++. The best diameter distribution from the algorithm was that making the trial untruncated-uncensored semi-trace length approximate to the observed one. Experiments to reduce the discreteness of the algorithm result were conducted. It is shown that taking mean value of many trials can reduce the discreteness effectively. The new trial algorithm is more accurate，better in fault tolerance，faster in calculation，lower in hardware configuration，less in file size and memory occupancy，more convenient in programming and more stable in running than Priest-Zhang algorithm. Also it suits more distribution patterns than Priest-Zhang algorithm and Huang Lei?s previous one. The new trial algorithm supplies the gap in the accurate algorithms for universal distribution patterns in semi-trace line-sampling，which has been tested in Wenchuan earthquake area and is worth popularizing.
2012, Vol. 31 
