For the problems of low nitrification yield and the use of highly toxic substances in the synthesis of high-energy oxidant 1，4-bis（trinitromethyl）-3，6-dinitropyrazole［4，3-c］pyrazole （ONPP）， a new synthetic process of ONPP was developed. The single crystal of ONPP was cultivated by slow evaporation from an ethyl acetate solution. The energy levels of different formulations based on ONPP were estimated. In the presence of base and phase transfer catalyst Bu₄NBr（TBAB）， 3，6-dinitropyrazole［4，3-c］pyrazole （DNPP） reacted with bromoacetone to introduce two acetone groups on pyrazole ring. Followed by nitrating with HNO₃/H₂SO₄/P₂O₅， ONPP was obtained in the total yield of 31%. Compared with the literature （10.4% total yield from two steps）， the yield of new synthetic route from DNPP increase by nearly three times. Meanwhile the use of highly toxic butenone is avoided， which is more suitable for large-scale production. The crystal structure of ONPP belongs to the monoclinic crystal system， P2₁/c space group. Its crystal density is 1.983 g cm^-3 at 293 K. Through the energy estimation of HTPB （10%）， Al （20%） and oxidizer （70%） formulations， the energy level is optimal when ONPP （40%） and AP （30%） are used together as oxidizers， which is significantly higher than the formulation energy levels when they used as single oxidant.