The quality and properties of steels may be affected due to the segregation of the alloying elements, even though the properties of steels can be improved by adding appropriate amount of alloying elements. Rapid solidification was regarded to be an effective method to reduce or eliminate the segregation of alloying elements. While the segregation of C, P and Mn was also observed in rapid solidified (in silicone oil) droplet carbon steels in this paper. The microstructures of rapid solidified droplets were rather fine. When the P content was less than about 0.09% (in mass) in low carbon steels, P did not show obvious segregation in rapid solidified droplet samples; when the P content raised up to about 0.5% in the samples, both P and Mn showed center segregation even though the content of Mn kept unchanged. So the alloying elements can segregate and even effect the distribution of other elements in rapid solidified steel samples. When the C content increased, the segregation of C was observed in high-C samples, while the segregation tendency is opposite to that of P in high-P samples. For all the droplet samples, the micro-hardness of high-P samples was also much higher than those samples with less P content.