Quantum statistical properties such as first-order coherence, antibunching, sub-Poisson distribution and the probability distribution of photon number are studied by considering the non-resonant interaction of two radiation fields with a ' Lambda ' structure three-level atom. It is found that the different detunings and the different ratios of average photon number of two radiation fields as well as the time regime have a remarkable influence on quantum statistical properties of the two radiation fields. The author also emphasises that the initial atomic state plays an important role in the non-resonant interaction and tries to explore the connections among these non-classical effects.