[en] The experimental value of radiative correction Δr was derived from the new data of sin²θ_W and W boson mass M_W given by LEP, CDF and other collaborations. A careful comparison of (Δr)_exp with the standard model expectation was carried out. The authors first calculated the Δr at full one-loop level, and then the main two-loop contributions were included. More stringent upper bounds on M_t were obtained from the analysis of probability distribution: M_t < 175 GeV at 95% C.L. for a given M_H = 100 GeV. The effects on M_t from other experimental and theoretical errors were also computed