The quantitative analysis of phosphorus in fertilizer was investigated by laser-induced breakdown spectroscopy (LIBS) in this paper. The atomic spectral lines of 255.3 and 844.6 nm for phosphorus and oxygen, respectively, were determined as the optimized line by analyzing the excitation energy, transition probability and interference elements. Eighteen samples were analyzed and fourteen of them were tested to construct the calibration curve of measured concentration of phosphorus, while the linear fitting degree of the calibration curve was 0.83. It should utilize more information of LIBS spectra to construct the multivariate nonlinear regression method, which can improve the measurement accuracy of LIBS. Compared with the calibration method, the correlation coefficient of the prediction concentration of LIBS with reference concentration was 0.98, and the relative measured error was greatly reduced, only in the range of 0.38%～1.70%. It is shown that LIBS has the potential for rapid analysis of phosphorus in fertilizer.