Abstract- In this paper, time frequency analysis of high harmonic generation in a tree color laser field has been discussed. For this purpose we used model atomic potential and absorbent potentials in order to reduce spurious reflections from the spatial boundaries in numerically solving 1D time dependent Schrödinger equation for Helium atom. Then, after making sure about the accuracy of the wave packet, we depicted the spectral distribution of high harmonics and their corresponding attosecond pulse. Thus, we explained them with the use of the applied time frequency analysis.