Cocatalysts play a vital role in accelerating the reaction kinetics and improving the charge separation of photocatalysts for solar hydrogen production.The promotion of the photocatalytic activity largely relies on the loading approach of the cocatalysts.Herein,we introduce a metal-seed assistant photodeposition approach to load the hydrogen evolution cocatalyst of platinum onto the surface of Ta3N5 photocatalyst,which exhibits about 3.6 times of higher photocatalytic proton reduction activity with respect to the cor-responding impregnation or photodeposition loading.Based on our characterizations,the increscent con-tact area of the cocatalyst/semiconductor interface with metal-seed assistant photodeposition method is proposed to be responsible for the promoted charge separation as well as enhanced photocatalytic H2 evolution activity.It is interesting to note that this innovative deposition strategy can be easily extended to loading of platinum cocatalyst with other noble or non-noble metal seeds for promoted activities,demonstrating its good generality.Our work may provide an alternative way of depositing cocatalyst for better photocatalytic performances.