Square root calculating is widely used in numerical analysis，modulation-demodulation，image pro? cessing and other fields. Applying Coordinate Rotation Digital Computer（CORDIC）algorithm to square root calculat? ing is a new application. However，the accuracy of the basic CORDIC algorithm must be guaranteed by the times of iterations，and a larger number of iterations will cause problems such as excessive delay. By using methods such as establishing look-up tables，one-way rotation，merging iterations，and eliminating compensation factors，an im? proved CORDIC algorithm that can eliminate most of the iterative operations is proposed for square root calculations. Compared with the basic algorithm to calculate the square root，the improved algorithm uses half the clock cycle to get the output result，greatly reduces the output delay，and can achieve high calculation accuracy，which is more suitable for applications with high real-time requirements.