An expression for premixed turbulent flame speed is presented, in which Reynolds number R-lambda, based on turbulent microlength scale lambda and turbulent intensity u＇, and Damkohler number Da defined as the ratio of characteristic residence time of turbulent flame to that of laminar flame, are considered to be the two controlling parameters. The constants involved in that expression are determined by regression with the available experimental data. It is found that the ratio of turbulent flame speed to laminar flame speed(V-t/V-l) increases with R-lambda linearly only when Da is kept fixed.