Abstract: The balance valve is installed in the none-rod cavity of the hydraulic cylinder to balance the external load on the rod, which can keep the length of the cylinder constant at static state in a short time and avoid the hydraulic cylinder stall in dynamic condition. But because of the leakage between the two cavities of the cylinder, the conventional cylinder can not keep the operation length constant for a long time under external load. The steel ball self-locking hydraulic cylinder has mechanical self-locking function at travel limit position. So, after antanna array is erected, the cylinder can keep the operation length constant for a long time, so as to ensure that the operation angle of the antenna array remains unchanged for a long time. The balance valve combined with the self-locking cylinder has double advantages of anti-stall and keeping length constant for a long time at limit position, but it appears time-delay actions when their parameters do not match. This paper studies the problem of parameter matching between the balance valve and the cylinder.