This paper devises an optimization framework for efficient energy management and components sizing of a plug-in fuel cell urban logistics vehicle. Based on the propulsion system structure, fuel cell system model, and convex battery health model, a convex programming problem is formulated to simultaneously optimize both the control decision and parameters of power sources, including a fuel cell pack and a battery pack. This paper seeks to minimize a summation of energy cost and power sources cost, while satisfying vehicle power demand and battery health requirements. Considering different drive cycles, the optimal parameters and energy cost are systematically investigated. As a result, the optimal battery rated power and energy capacity are about 54 kW and 29 kWh, respectively, which are not affected by different drive cycles, given an electric-only range between 40 km and 60 km. Finally, based on the developed convex programming control law and optimal parameters, we examine the power distribution of the plug-in fuel cell urban logistics vehicle with different hydrogen prices, which significantly influences the vehicle's fuel economy.