What alternative can be used to cure hemorrhoids? Is there any other thing to do to avoid the surgical operation?

It all depends on the severity of the condition. Have you tried Preparation H or other ointments?

Buy some inexpensive "witch hazel" and put in the fridge. When it's cold, soak a cotton pad with it and apply to hemorrhoid. Let dry. Dab on small amount of DMSO (Dimethyl Sulfoxide)
It acts as an anti inflammatory among other things. It is often found in a cream containing aloe vera gel which can only help matters.
Mostly, you should try to prevent them in the first place. Prevent constipation, straining for BM's and sitting long periods.

You can try using a lemon wedge and push it into the rectum. Just leave it there and it will leave with your next bowel movement. It will tighten the tissue and pull up the hemorrhoids. Try this if your condition is a temporary one and not chronic and you may find they never come back, or only come back after many years. If you have a chronic condition I don't know if this is advisable or will get you over the hump. Sometimes our bodies express underlying psychological stresses to get our attention in a variety of painful ways, and, this can shift from one symptom to a different symptom. So you might solve your hemorrhoid issue only to find that you later get a gas issue or something, because you haven't addressed the underlying cause. So, looking within to identify a possible psychological reason for the hemorrhoids might be the best thing you could do rather than trying to defeat the body's signal for you to stop and change course in some way.