This paper first designed the theoretical model about firms foreign investment, and then had an empirical study based on the datum of Korean manufacturing firms in China , finally it drew a conclusion: the research model centers on the factors of the firms, strategy and location, which has applicability for explaining developing countries’ foreign investment model; the differentiation advantage of the firm’s products and the export base strategy influence the choice of the wholly-owned subsidiary way; the Chinese market oriented strategy and the limitation in policy of Chinese government to overseas-funded firms influence the choice of the joint venture way.