An experimental investigation of the coherent population trapping (CPT) resonance excited on the D1 line of 87Rb atoms by bichromatic parallel linearly polarized laser light is presented. The experimental results show that a lin‖lin transition scheme is a promising alternative to the conventional circular-circular transition scheme for an atomic clock. Compared with the circular light transition scheme, linear light accounts for high-contrast transmission resonances, which makes this excitation scheme promising for CPT atomic clock.