The planar wire array Z pinch experiments with insulated aluminum wires coated with 2 μm polyimide were carried out on "QiangGuang-I" facility (100ns, 1.3 MA) and compared to those with ordinary aluminum wires. Experimental results indicate that surface insulation can affect the implosion dynamics and radiation character of Z pinches. The resistive heating energy and imploding mass may be increased by exploiting the effect of surface insulation. In the surface-insulated wire array Z pinch experiments the multi-peak phenomena were considerably suppressed, whereas the improvement on the X-ray yield was not observed.