Objective To improve the preparation of bronchoalveolar lavage fluid (BALF) in mice. Methods BALB/c mice were divided into 3 groups. In the first and second groups, the whole lung lavage was performed with the traditional method, using a vein detained needle and lavaged with sterile saline. The mice in the third group got whole lung lavage by the improved method, namely, using a self-made plastic rigid pipe connected with a syringe. Each mouse was lavaged for 3 times, with 0.5 mL of sterile saline for each time, and the time consumption was recorded. The collected BALF was centrifuged, the supernatant was separated and its volume was measured accurately. Results The time spent for BALF collection in each mouse in the third group was (4±0.62) min, significantly shorter than that of (10±0.75) and (12±0.88) min, respectively in the first and second groups (P< 0.05). The volume of BALF collected in each mouse of the third group was (1.34±0.16) mL, significantly higher than that of (1.03±0.25) and (1.13±0.22) mL, respectively in the first and second groups (P< 0.05). Conclusions The improved method of BALF collection described in our study is simple, economical and efficient, and is useful for beginners especially.