To cool and focus the Cr atoms, the laser frequency must be locked to the 425.55 nm 7S3→7P04 transition of 52Cr in the research of Cr atom deposition. A see-through Cr-He hollow cathode discharge cell is designed and fabricated to sputter the atom vapor of Cr. Polarization spectroscopy is applied to lock the laser frequency. This technique not only simplifies the experimental equipment but also increases the efficiency. A high signal-to-background ratio dispersion signal is obtained without any modulation device or lock-in amplifier. This signal is used as error signal to lock a frequency-doubled Tisapphire laser to the 7S3→7P04 transition of 52Cr. A frequency fluctuation of ±295 kHz for more than one hour is achieved. The experimental results show that this technique is feasible to lock laser frequency to transitions of metals with high melting point.