In this paper, a high effective up-conversion luminescence agent (Er 3+ :Y 3 Al 5 O 12 ) is synthesized by sol–gel method, and then its corresponding visible-light photocatalyst (Er 3+ :Y 3 Al 5 O 12 /Pt–TiO 2 ) is successfully prepared by direct mixing and calcination methods. For comparison, Er 3+ :Y 3 Al 5 O 12 , Pt–TiO 2 and Er 3+ :Y 3 Al 5 O 12 /Pt–TiO 2 are all characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). At first, the up-conversion luminescence properties of Er 3+ :Y 3 Al 5 O 12 are reviewed by excitation spectrum in visible-light region and emission spectrum in ultraviolet-light region. And then, under visible-light irradiation the visible-light photocatalytic activity of Er 3+ :Y 3 Al 5 O 12 /Pt–TiO 2 is examined through photocatalytic hydrogen production from aqueous methanol solution. Lastly, the influence factors such as Er 3+ :Y 3 Al 5 O 12 and Pt–TiO 2 mole ratio, heat-treated temperature and heat-treated time on the visible-light photocatalytic hydrogen production activity of Er 3+ :Y 3 Al 5 O 12 /Pt–TiO 2 are studied. Particularly, Er 3+ :Y 3 Al 5 O 12 /Pt–TiO 2 with 6:100 M ratio heat-treated at 550 °C for 90 min shows the highest photocatalytic activity in hydrogen production from aqueous methanol solution.