Multiunit structure can internalize the managerial market to promote competition among subsidiary managers, and create an internal capital market within firms to alleviate external financing constrains, and it also may lead to diversification to lower the operation risk and regulation. While it brings in more agency problem created by subsidiary managers, causing the efficiency of internal capital market and diversification confusing. Using the data of listed firms in China, an emerging market, this paper examines the efficiency of multiunit structure within the firm, investigating the influence on capital allocation and firm performance. We find that multiunit structure is better in emerging market since it is efficient in capital allocation, reducing the inefficient investment by reducing the overinvestment and alleviating the underinvestment, and the bright side of multiunit structure dominates the agency problem associated, thus beneficial for firm performance, both short-term and long-term accounting returns. In less developed capital market under current situation, multiunit structure is better.