A current control device and a power conversion system employing the current control device are provided. The current control device controls N power conversion unit(s), where N is a positive integer. The N power conversion units are connected in parallel when N is greater than 1. Each power conversion unit includes a signal input terminal and a current-controlled output terminal electrically connected to an external circuit. The current control device includes a first current sensor and an error compensator. The first current sensor samples a current flowing through the external circuit and acquires a sampling value. The error compensator receives the sampling value and a reference value and generates a compensation value accordingly, and outputs N current command(s) to the N power conversion unit(s) respectively according to the reference value and the compensation value.