Sandpit is an important outdoor playground for children. Moreover, it also has good rainwater permeability, which makes it easy to accumulate pollutants that accompany the surrounding surface runoff. Therefore, children playing in the sandpit face the health risk of heavy metal pollutants entering the body. A method for quantitative and rapid detection of the characteristics of heavy metal pollution in children’s sandpits in Beijing using the X-ray fluorescence spectroscopy (XRF) analyzer was introduced in this study. The results showed that: (1) The relative standard deviation and relative error between the measured values and theoretical values of Pb, Cu, As, and Cd in the self-made standard samples by XRF were -1.3%～7.5%, and 1.1%～5.3%, respectively, which were all consistent with the requirements of instrument testing specified in the relevant environmental quality testing technical specifications (less than 10%). (2) There was a very significant positive correlation between the measured values and the theoretical values of the four heavy metals (p<0.001), and their coefficients of determination (R2) were 0.999, 0.999, 0.996, and 0.998, respectively. The results established fitting equations of measured and theoretical values; (3) XRF was used to determine the heavy metal content of children’s sandpits in 17 parks and 13 residential areas in Beijing. The Pb and As content in the two groups of samples were significantly different, but there was no significant difference between the Cu and Cd content. The coefficients of variation of the standard deviations of the four heavy metals ranged from 0.24~0.43. These values were all greater than 0.3, except for Cd, which indicated significant spatial variability; (4) Compared with the background values of soil elements in Beijing, the average content of Pb, Cu and Cd in children’s sandpits was significantly higher, which were 1.87 and 1.53, 1.79 and 2.23, 12.02 and 11.68 times, respectively. It can be seen that Pb, Cu, and Cd are enriched in different degrees in children’s sandpits at sampling sites, and their health risks cannot be ignored. XRF can provide accurate and fast data support for managing and maintaining children’s playgrounds.