Abstract: In view of the problem that the production testing and the production profile monitoring for horizontal wells in deep water oilfield in the eastern South China sea cannot be implemented effectively, by using the mechanism of Noyes-Whitney and Higuchi, the oil-soluble and water-soluble tracers were prepared, the tracer string suitable for horizontal wells has been designed, and a set of sampling and interpretation methods have been developed, which was the first successful trial in the country. The process of technical testing does not require the use of pipe string and can realize long-term safety monitoring, which solves the problems of complicated operation and high risk in production logging for common horizontal wells, and overcomes the difficulties in production testing and production profile logging for horizontal wells in deep water oilfield.