The soil-nailed wall is widely applied to the support of foundation pit in recent years,and many achievements have obtained,but the load instability occurs in some soil-nailed walls because of certain reasons.In this paper,taking the some project as example,the factors influencing the stability of the foundation pit are analyzed,the causes of the failure are found out from geological condition,design and construction and so on.A solution scheme was put forward,the good effect was achieved after the implement of the solution scheme.