A three-dimensional printer with detecting printing accuracy and a method for detecting printing accuracy is provided. The three-dimensional printer with printing accuracy detection includes a three-dimensional model conversion unit, a printing path locating unit, a printing path drawing unit, and a comparison unit. An actual printing path is drawn according to the real-time captured location information of a nozzle head of the three-dimensional printer and compared with a predetermined printing path, which may implement the detection of printing accuracy. The method for detecting printing accuracy may implement the accuracy detection of the three-dimensional printer and be capable of detecting the accuracy for the three-dimensional printer. The method for detecting printing accuracy also reminds an operator to check and maintain printing accuracy of the three-dimensional printer.