Multiphoton ionization (MPI) mass spectra distributions of tetramethylsilane in gaseous phase are investigated using a quadrupole mass spectrometer and a pulsed molecular beam at 355 nm laser radiation. The dependence of the signal intensity of the ions Si(CH 3) + n (n=1,2,3,4) and Si + on laser power is measured. The fractions of signal Si(CH 3) + n(n=1,2,3,4) and Si + vs. laser intensity are obtained. According to these, the possible MPI channels and the chemical kinetics mechanisms of this molecule are discussed. The conclusion is gained that Si + ions might be mainly produced via a sequential photo-dissociation to form Si atoms first and followed by a multiphoton ionization of Si atoms, Si(CH 3) + n(n=1,2,3) ions might be mainly produced from self-ionization of neutral fragments Si(CH 3) n, and the Si(CH 3) + 4 ions might be produced from (3+1) ionization of parent molecules.