By applying the laser absorption and fluorescence method, the cross sections for the fine structure mixing and quenching of the Cs(6P) state, induced by collision with He atoms, have been measured. Cesium atoms were optically excited to the 6P3/2 state. The excited atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single mode laser beam, which was tuned to the 6PJ→8S1/2 transitions. The effective radiative rates were calculated for the 6PJ→6S transitions. The fluorescence intensity I895 of the sensitized 6P1/2→6S1/2 emission was measured as a function of He density in the range 0.5×1018～4×1018cm-3 at constant temperature T=337 K. It was found that the quantity N/I895 exhibited a parabolic dependence on N, confirming that the quenching of the 6PJ states was due to collision with He atoms, not ground state Cs atoms. The coefficients of the second-order polynomial fitted through the measured data yielded the cross sections σ3/2→1/2=(1.46±0.51)×10-19 cm2 and σD=(2.28±0.80)×10-18 cm2 for the 6PJ fine structure mixing and quenching, respectively, due to collision with He atoms.