Abstract: By using the algorithm of B-spline surface representation，initial B-spline surface control lattice was constructed to approach scattered data sets at first，on the basis of which the bounding box was designed to search locally and to detect the error，and to transfer finding problem into computing problem.To deal with small elements via element condensation，the regional numbers of the exceeding errors are reduced and surface is optimized in the region of the exceeding errors，then surface reconstruction and its optimization are realized from coarse to fine.The algorithm is modified in the error detection and regional processing so that the searching is more quick and computing is simplified. Thus the speed has been quickened and the computing is much easier.It is also proved that the computing is easy and feasible to make，and the approximating effect is quite good.

Key words: hierarchy B-spline, surface reconstruction and optimum, bounding box, element condensation, scattered data