Abstract: A solubilized plant growth regulator includes a mixture mainly containing a hiba oil, ethanol, polyoxyethylene sorbitan monolaurate or another surfactant or a nonionic surfactant prepared from a higher alcohol. Alternatively, such a solubilized plant growth regulator includes a stirred mixture mainly containing a hiba oil, a sucrose fatty acid ester, ethanol, propylene glycol, polyoxyethylene sorbitan monolaurate or a nonionic surfactant prepared from a higher alcohol, and water. The plant growth regulator has substantially no toxicity to the human body and high insecticidal/insect-repellant and antimicrobial activities.