Edit the passage please.

D-V.SN, established on July 18, 2003, is a web site on biological and medical technology. Since that time we have dedicated ourselves to providing a professional platform for communication between people specializing in the field of life and medical science. Devoted to professionalism and the accumulation of knowledge, we have developed from a message board for a few membes to a large-scale site for millions.

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My changes in italics--not bad, but you need to work on your use of the definite article. You used it inappropriately twice, and then failed to use it when it was appropriate.

Thank Setanta.

I left out the last sentence " It is now the largest and most popular medical platform in our country with more than 1,950,000 members who specialize in medicine, pharmacy and life science. "

Because we have used "specializing" once, so I feel we need to use another word to substitute "specialize" here. What word can we have? Or we don't need to change?

In addition, which is better? "Who specialize in medicine, pharmacy and life science" or "who specialize in medical, pharmaceutical and life sciences"?

You don't need to worry about using specialize, its meaning is specific enough that it would be silly to try to replace it--just go with it. Your second question is a poser, since the term life sciences is far and away the most common usage--in fact, i've ever seen life science used rather than life sciences. Also, the definite article is usually used with life sciences. Let's go with: "who specialize in medical, pharmaceutical and the life sciences."