这是你想要的吗？

static void Main(string[] args)
    {
        X509Certificate2 cer = new X509Certificate2();
        cer.Import(@"D:\l.cer");
        X509Store store = new X509Store(StoreLocation.CurrentUser);
        store.Certificates.Add(cer);

         X509Certificate2Collection cers = store.Certificates.Find(X509FindType.FindBySubjectName,"My Cert's Subject Name",false);
        if (cers.Count>0)
        {
            cer = cers[0];
        };
        store.Close();
    }