As an innovative mode of supply chain finance, financing service offered by a third part logistics (3PL) firm has been practiced over the recent years. This paper investigates the optimal operational strategies of the supply chain system consisting of a supplier, a capital-constrained retailer and a 3PL firm. In this study, we compare the optimal operational strategies under both decentralised and centralised decisions, and put forward the supply chain coordination condition when the 3PL firm offers financing service. Several important results are achieved. First, the supplier’s wholesale price strategy has obvious influence on the decisions of the retailer and the 3PL firm. Second, the retailer’s ordering quantity under 3PL financing service is more than that without any financing service; and it can exceed the ordering quantity of a well-funded retailer, if and only if the supplier’s wholesale price and the 3PL’s interest rate meet certain conditions. Finally, we find that under 3PL financing service, the profit of supply chain can achieve Pareto improvement, and the wholesale price contract may realise profit maximisation and channel coordination in the supply chain system under certain condition.