Should a program I have not finished yet be mentioned in the SOP? I have followed a program three months ago, which I haven't get a satisfying outcome. It is in the field I am interested in, but the technology and skills required in it is something related not so relative to my major. Besides, since I am spending time preparing for an entrance exam for a graduate school, I cease doing research in the program.

As I haven't get good outcome and I don't want to do research in the chemical way in the future. What should I say in the SOP? should I mention the experience, as it is the only one experience in academic research during my undergraduate years?
If the experience was positive for you in some way, then sure, you can talk about it.  For example, perhaps it gave you a greater appreciation for what research entails, or the scientific method, or it made you excited to get to school every day, etc. etc.

If you only have one sentence about it, then don't include it in the essay.  You can always mention it briefly somewhere else in the application.