The B-spline finite element method in polar coordinates for solving some waveguide eigenvalue problems is described. The technique has two main advantages: （1）Avoiding thesubdivision errors at some curved boundaries 1 （2）Improvement on the computational accuracy for asharp corner existed in the waveguide cross section. The B-spline finite element equations in the 0p coordinate system are established. The method is used to solve the eigenvalue problems in circular

sector

double-ridged circular

and heart waveguides. The numerical results are compared withthe exact solutions and those obtained by the traditional finite element method in polar coodinates

which demonstrates that the present method is convenient to implement

and leads to a high computational accuracy and substantial saving in computer storage and time.