This article presents an analytical model of the interturn short-circuit fault in interior permanent magnet synchronous motors (IPMSMs) with multistrand windings. The proposed model covers possible failure modes due to insulation degradation. With a coil as the basic unit, this model has considered the spatial layout and mutual inductance of motor windings. Compared to other mathematical models, this model has made substantial progress in authenticity and reliability. The model is controlled through closed speed and current loops, which is consistent with most application scenarios. This model can be used to study the postfault behavior of IPMSMs under transient and steady states. An experimental setup is built, and validation experiments under various fault modes and operating conditions are conducted. The fault currents obtained using the proposed model are in good agreement with the experimental results, confirming the value and potential of the proposed model in understanding such faults and developing automatic fault diagnosis methods.