Hydrogen absorptions of LaFe11.5Si1.5 compound in 1-atm hydrogen gas at different temperatures are investigated.The hydrogen content in the hydrogenated sample does not increase with the increase of temperature of hydrogenabsorption but changes complicatedly.The characteristic offirst-order transition in LaFe11.5 si1. 5 compound is weakenedafter hydrogen absorption.It leads the peaks of magnetic entropy to become wider and the hysteresis loss to reducesignificantly,but relative cooling power(RCP)is not changed considerably.