A new modification in a practical method for directional spectrum parameters by HF radar is presented. This new method is a further modification of Bayesian method reported by Hashimoto and Tokuda (1998). In this paper, a formulation of directional spectrum is characterized by an exponential function having the power expressed by a Fourier series over the directional range and assumed to be a piecewise-constant function over the frequency range. The applicability and accuracy of the proposed method are comprehensively examined using numerical simulation and field data of various wave conditions. The results suggest that modified method provides several advantages more powerful, potentially more accurate and faster solution techniques in practical method.