Various errors in machine tools can significantly impact the final quality of machining, with geometric errors being the primary source of such influence. Geometric errors comprise a combination of multiple factors, including angular, positioning, straightness, and perpendicularity errors across the machine’s axes, amounting to 21 different types. Typically, correcting these errors requires the use of a laser interferometer. However, the complex operation of laser interferometers leads to lengthy setup times, and the high cost of the laser equipment, including the necessary mirrors for different error measurements, further complicates the process. Additionally, the precision required by laser measurements necessitates a clean and stable environment, often resulting in considerable time loss during measurement. Consequently, many opt to extend the calibration intervals to reduce costs, which makes it difficult to capture dynamic geometric changes in the machine during operation. Failure to promptly assess the machine’s health can lead to suboptimal machining quality and precision, increasing production costs. This study proposes a straightness error measurement system designed to significantly reduce the time cost associated with error measurement. The system involves installing an eddy current micro-displacement sensor, with an accuracy of 1.3 µm and a resolution of 200 nm, into an orthogonal measurement device mounted on the tool-holder. Using a ball array as the workpiece, the system measures the errors between each measurement point in the array, calculating the machine’s horizontal and vertical straightness. The obtained error values are then input into the CNC controller for compensation. This method reduces the reliance on high-precision instruments and minimizes downtime associated with maintenance, thereby lowering overall time costs.