In order to study the performance of red sandstone soil solidified by biological enzyme soil curing agent and cement, and to explore the feasibility of composite solidified red sandstone soil used in expressway subbase, the effects of biological enzyme soil curing agent dosages on mechanical properties and durability of solidified soil were carried out, and microscopic tests were carried out in combination with scanning electron microscopy to analyze the stability mechanism. The results show that the addition of biological enzyme soil curing agent improves the unconfined compressive strength, splitting tensile strength, penetration resistance strength and elastic modulus of solidified soil, and the optimal dosage is 2. Under the same stress ratio, the fatigue life of composite solidified soil has no obvious advantage compared with that of single solidified soil by cement, but under the same stress, the fatigue life of composite solidified soil increases significantly compared with that of single solidified soil by cement. This study provides a reference for the practical engineering application of composite solidified red sandstone soil in expressway subbase.