The present invention disclose a catalytic system of using visible light to photodecompose water to produce hydrogen, and particularly a visible light catalytic system with a copper ion-thiol complex, a preparation method, and a hydrogen production method. The system comprises the following raw materials: a semiconductor photocatalyst, a copper salt or a copper ion-thiol complex and a thiol compound. The preparation method comprises: using a semiconductor material as a photocatalyst; using a thiol compound as a hole consumption agent; adding a copper salt or copper ion-thiol complex; photodecomposing water to produce hydrogen under irradiation of visible light (lambda > 400 nm). The copper ion-thiol complex of the present invention has the effect of promoting hole transport and consumption in a semiconductor, and can increase efficiency of separation between photogenerated electrons and holes in a semiconductor photocatalytic system, thereby improving activity of the system in photodecomposing water to produce hydrogen. The present invention proposes the copper ion-thiol complex as a hole consumption cocatalyst in the photocatalytic system, and the cocatalyst is high in catalytic activity, simple in synthesis, low in raw material price, and recyclable.