在您的上下文中尝试此操作：

public class MyDatabase : DbContext
{
    public MyDatabase ()
        : base(ContextHelper.CreateConnection("Connection string"), true)
    {
        ((IObjectContextAdapter)this).ObjectContext.CommandTimeout = 180; // seconds
    }
}

如果要在连接字符串中定义超时，请使用Connection Timeout以下连接字符串中的参数：

<connectionStrings>

<add name="AdventureWorksEntities"
connectionString="metadata=.\AdventureWorks.csdl|.\AdventureWorks.ssdl|.\AdventureWorks.msl;
provider=System.Data.SqlClient;provider connection string='Data Source=localhost;
Initial Catalog=AdventureWorks;Integrated Security=True;Connection Timeout=60;
multipleactiveresultsets=true'" providerName="System.Data.EntityClient" />

</connectionStrings>

来源：如何：定义连接字符串