public class CustomReportCredentials : Microsoft.Reporting.WinForms.IReportServerCredentials
    {

        private string _UserName;
        private string _PassWord;
        private string _DomainName;
        public CustomReportCredentials(string UserName, string PassWord, string DomainName)
        {
            _UserName = UserName;
            _PassWord = PassWord;
            _DomainName = DomainName;
        }
        public WindowsIdentity ImpersonationUser
        {
            get
            {
                return null;  // not use ImpersonationUser
            }
        }
        public ICredentials NetworkCredentials
        {
            get
            {

                // use NetworkCredentials
                return new NetworkCredential(_UserName, _PassWord, _DomainName);
            }
        }
        public bool GetFormsCredentials(out Cookie authCookie, out string user, out string password, out string authority)
        {

            // not use FormsCredentials unless you have implements a custom autentication.
            authCookie = null;
            user = password = authority = null;
            return false;
        }
    }

Microsoft.Reporting.WinForms.IReportServerCredentials ir=new CustomReportCredential("username","pwd","domain"); 
this.reportViewer1.ServerReport.ReportServerUrl = new Uri("http://192.168.0.1/reportserver");
this.reportViewer1.ServerReport.ReportPath = "/无标题";
this.reportViewer1.ServerReport.ReportServerCredentials = ir;