We numerically investigate the high-order harmonic generation with two-colour optical field,taking into considera-tion the propagation effects.Some harmonics can be dramatically enhanced at a certain delay between the fundamental pulse and its second harmonics.Choice of the enhanced harmonics can be realised by changing the time delay between the two laser pulses. We numerically investigate the high-order harmonic generation with two-color optical field, taking into account the propagation effects. Home harmonics can be dramatically enhanced at a certain delay between the fundamental pulse and its second harmonics. Choice of the enhanced harmonics can be realized by changing the time delay between the two laser pulses.