Abstract: Considering the flexibility of the fiber placement head and the small width of the towpreg,a new trajectory planning algorithm of automated fiber placement,namely,variable-angles trajectory planning algorithm,is presented.And the placed variable angles plies have no gaps and no overlapping.Taking the conical shell as an example,the mathematical model of geometric features of the conical shell is built up first.Then the mathematical equations of any trajectory on the conical shell surface can be derived.After introducing the theory and method of forming of variable angles plies,the mathematical model of variable angles trajectory planning algorithm is addressed and the mathematical equations of curvature of any trajectory is derived.The manufacturability of the variable angles plies has been analyzed.At last,through the simulation experiment of fiber placement,the variable angles trajectory planning algorithm has been proved.