In engineering construction, cement quality directly affects the safety of construction projects. So it is necessary that we use qualified cement in the engineering structure. It is of great signification that a method detects cement raw material rapidly to adjust the mixture ratio of raw ores to ensure the cement quality. Traditional detection method needs sampling, sample preparation and test, etc. With many procedures, the test results are seriously lagged behind the production process. This paper introduces a set of online analysis equipment to determinate elemental composition of cement powder timely based on laser induced breakdown spectroscopy. This equipment is composed of a LIBS detection system and a pneumatic system. The equipment can achieve the real-time measurement for it needn’t sample preparation. Thus, it can guide cement raw material proportioning in time. In this paper, we have quantitatively analyzed the main components of Al2O3, CaO, Fe2O3, MgO and SiO2 in the cement raw materials using the full spectrum normalization method as well as the support vector machine. The corresponding maximum absolute errors were 0.34%, 0.35%, 0.07%, 0.14%, and 0.55%, respectively. Results showed that the measurement results of the newly developed LIBS equipment are in accord with those of the conventional chemical method. Furthermore, the measurement precision is in line with X-Ray fluorescence spectrometry. It is confirmed that the LIBS technique could be a prospect method for determination of elemental composition in the cement production industries.