The invention discloses an aluminum alloy and plastic-steel thermal insulation composite sliding door leaf profile. The profile comprises a leaf material inner part made of a plastic-steel material and a leaf material outer part made of an aluminum alloy material. The leaf material inner part and the leaf material outer part are clamped, sleeved and matched and are oppositely provided with pulley installing grooves, lock bar installing grooves and glass installing grooves in sequence in the direction from an outer frame edge to an inner frame edge, thermal insulation cavities are formed between the pulley installing grooves and the glass installing grooves, and the lock bar installing grooves are formed between the thermal insulation cavities. According to the composite sliding door leaf profile, through the characteristic that the plastic-steel material is poor in heat conductivity and the characteristic that aluminum alloy is high in strength, the leaf material inner part made of the plastic-steel material and the leaf material outer part made of aluminum alloy are combined to form the sliding door leaf profile, the sliding door leaf profile has good thermal insulation performance and high strength, and the service life of a sliding door leaf is guaranteed. The thermal insulation cavities are additionally formed, and therefore the overall thermal insulation effect of the composite sliding door leaf profile is further enhanced.