Oxo derivatives of pyrazolines and pyrazolidines are important heterocyclic compounds due to their unique biological activities and have been widely applied in pharmaceutical and agromedical fields. In this review, we provide an account of some recent advances in the field of pyrazolone chemistry, specifically on the reported synthesis methods of pyrazolinone (3-oxo-1,2-dihydropyrazole) and 3,5-pyrzolidinediones (3,5-dioxotetrahydropyrazoles) derivatives.