In order to suppress the long-term frequency drift of CW lasers, continuous laser modulation-free frequency stabilization can be realized by computer control with precision wavelength meter as reference frequency standard. The method obtains the wavelength meter data from computer, and the feedback voltage value output to laser is calculated by using digital proportion-integral-derivative (PID). Thus the laser cavity length is modified, and the laser frequency is locked. This method can be applied to any given wavelength within spectral range of a commercially available laser, and can lock the laser to any absolute frequency within its tunable frequency range. The locking of 631 nm external cavity semiconductor laser is achieved with this method, and the stable locking with frequency uncertainty of 7.4 MHz for an hour, long-term frequency drift rate of ±1.1 MHz/h is obtained.