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From the previous research result it can be found that fine particle congregates most of the nocuous matter of aerosol. These matters can enter into respiration system of humanbeing, and be deposited in the alveolus. Fine particles seriously affect people's health, and make environment even worse. Experts have attached great importance to the research in this field. The background,project,science policy and problem of the PM 2.5 research in New York City are given. The measurement sites and some already acquired primary results are particularly introduced in order that all these can provide some help to similar research in China.