Four types of wire-arrays were investigated in Z-pinch experiments on JULONG-I, in which axially resolved x-ray radiations were measured by using one-dimensional imaging system. X-ray radiations rose up significantly later near electrodes than at other main positions. The radiation intensity was weaker near anode than other positions. The optimized value of product of wire-array line mass and the square of wire-array radius (called MR2) for a 20mm diameter wire-array on JULONG-I was found to be approximately 0.9mgcm. Further, there was a clear correlation between axial radiation synchronization quality and radiation power.