环丙烯是三个碳的环烯烃，分子式为C₃H₄。由于具有张力，环丙烯具有一些和其他环烯烃不同的性质。

Cyclopropene is an organic compound with the formula C₃H₄. It is the simplest cycloalkene. It has a triangular structure. Because the ring is highly strained, cyclopropene is difficult to prepare, and a useful core for studies of bonding and molecular orbitals. The reduced length of the double bond compared to a single bond causes the angle opposite the double bond to narrow to about 51° from the 60° angle found in cyclopropane. As with cyclopropane, the carbon–carbon bonding in the ring has increased p character: the alkene carbons use sp hybridization for the ring.