The electric solar sail (Esail) is a new propulsion concept which can extract momentum from the solar wind almost without comsuming any propellant. The dynamic characterisitcs of a Esail system composed of two microsatellites connected each other by tethers were investigated. The Esail system was modelled by adopting the dumbbell model assumption accounting for the attitude of electric solar sail, which was neglected in traditional models. Numercial simulations based on heliocentric nonkepler orbits were carried out to evaluate the propulsion performance under the coulomb force from the solar wind. The simulation results indicated that the propulsive efficiency of the Esail was largely influenced by the lengths and voltages of the tethers, the masses of the satellites and the pitch angle with respect to the flight direction.