In this paper, we propose an automatic parameter configuration mechanism for GridFTP, which optimizes the number of parallel TCP connections by utilizing analytic results in [1]. The proposed mechanism first measures the network status (e.g., the goodput and the round-trip time of GridFTP data channels) at the GridFTP client. Based on these measurement results, it adjusts the number of parallel TCP connections for maximizing the GridFTP goodput. Three operational modes, MI (Multiplicative Increase), MI+ (Multiplicative Increase Plus), and AIMD (Additive Increase and Multiplicative Decrease) are proposed in this paper, each of which takes a different strategy for adjusting the number of parallel TCP connections. We evaluate performance of the proposed automatic parameter configuration mechanism through simulation experiments. We demonstrate that the proposed automatic parameter configuration mechanism significantly improves the performance of GridFTP.