为实现电火花加工小孔圆柱度误差的合理控制，通过工艺试验研究了放电参数与小孔圆柱度间的规律。提出了多截面直角坐标测量方法，用线切割对已加工小孔的工件进行轴向和径向切割，以产生反映小孔特征的母线基准和圆基准；然后，用万能工具显微镜对这两个基准上的特征点进行测量，最终实现小孔圆柱度的定量评定。在此基础上，采用正交试验研究了放电参数(开路电压、电流，脉宽，脉间，抬刀周期)对小孔圆柱度的影响。结果表明，脉宽对圆柱度的影响最为显著，开路电压次之，其余3个参数的影响较弱；实验获得了以圆柱度误差最小为评价目标的一组放电参数：开路电压110 V，电流0.6 A，脉宽150 μs，脉间120 μs，抬刀周期1+2 s。验证实验得到了平均半径为0.301 84 mm的小孔，其圆柱度误差为0.021 mm，说明用该方法控制电火花加工小孔的圆柱度是有效的。

In order to control the cylindricity errors of small holes machined by Electrical Discharge Machining (EDM), the relations between the electrical parameters and the cylindricity of small holes was studied by technologic experiments. In the course of studying, a multi-cross section measuring method in a Cartesian coordinate was proposed. The Wire Electrical Discharge Machining(WEDM) was used to cut the processed workpieces in axial and radial directions to obtain the generatrix datum and circle datum of machined small holes, then the characteristic points of two data were measured by an universal tool microscope, and the cylindricity quantitative evaluation of the small holes was realized. Based on the method above, an orthogonal experiment was carried out, and the effect of some main electrical parameters (voltage, current, pulse duration, pulse interval and tool-lifting) on the cylindricity of small holes was studied. The results indicate that the pulse width affects cylindricity most distinctly, the voltage comes second, and the effect of rest parameters show a bit weaker.A sets of discharge parameters are achieved to purchase the least cylindricity error, which are V=110 V, I=0.6 A, ton=150 μs, toff=120 μs and tool-lifting time=1+2 s. In the experiment, a small hole with a average radius of 0.301 84 mm can offer the cylindricity of 0.021 mm,which means the presented method is effective to control the cylindricty of the small holes machined by EDM.