In order to achieve the influence of different pretreatment methods on heat pump dried tilapia fillets, the effects of trehalose, ultrasound-assisted and freeze-thaw cycle assisted osmotic dehydration on the color, rehydration, texture and Ca2+-ATPase activity were investigated. Tilapia fillets (100 mm length × 50 mm width × 5 mm height) were first osmoconcentrated in a trehalose solution combined with 4°C under atmospheric pressure for 1 h, different power of ultrasound and freeze-thawing respectively, then heat pump drying. The results showed that under the same drying method, the comprehensive score of ultrasound in 400 w was best, compared to freeze-thaw, the ultrasound pretreatment had a significant (P<0.05) effect on the color and Ca²⁺-ATPase activity, but had no significant (P>0.05) effect on the rehydration and texture. However, both of them significantly (P< 0.05) affected the quality in comparison to that of osmosis at 4°C. It indicates that suitable ultrasonic pretreatment conditions improve the quality of dried products effectively and the conclusion of this research provides reference for heat pump dried similar products.