Abstract: Gradient Projection Method always results in great variations in joint velocity when it is used for fault tolerant trajectory planning of redundant robots. To solve the problem, this paper introduces Weighted Least Norm Method into fault tolerant trajectory planning. Theoretical analysis and simulation research on BUAA-RR redundant robot show that using Weighted Least Norm Method can obtain more smooth joint velocity, which concludes that it is a effective fault tolerant trajectory planning algorithm.