Abstract: Foam concrete is a new port terminal retaining wall backfill material, with such properties as lightness, strong independence and anti-water, and the foaming agent is very important for the properties of foam concrete. The improved foam concrete foaming agent is a concentration of 0. 8% AOS solution as foaming agent mother liquor, selecting a stable foam material A, B, C, and D to modify mother liquor, and the foam properties were analysed. The foam surface of this foam concrete foaming agent was smooth and lucidus, with foam stability was fine, and the foam multiple was 46. 7, 1h sedimentation distance was 1. 2mm, 1h secretion of water was 15. 7 ml. The foaming agent was used to prepare foam concrete for retaining wall backfilling, and the products showed good mechanical properties and anti-water performance.