At present, formed winding is usually used on high-voltage motor stator with open slots matched, which leads to a series of problems such as increasing motor cost, increasing air gap magnetic field harmonic content, and increasing cogging torque. The above problems can be solved by using scattered round copper wire winding. The insulation of scattered windings used in high-voltage motors is the focus of attention and research. Taking a high-voltage scattered winding motor as an example, the reliability of the insulation structure of the high-voltage motor using scattered windings is analyzed by finite element method. The insulation conditions of the turn-to-turn insulation, the main insulation, the interlayer insulation and the end insulation, and the electric field intensity distribution when the main insulation is scratched by the burrs of steel sheet are analyzed respectively. According to the analysis results, the insulation in the motor slot is optimized. A prototype is manufactured and a voltage withstand test is conducted on the prototype. It is verified that the use of scattered windings in the stator of high-voltage motor is feasible to a certain extent, which provides a reference for the design of the stator insulation structure of the high-voltage motor.