Take the Orange Line 4 (4B) to Xinzhuang station (新莊). After leaving Exit 1, take a right, followed by another immediate right. Follow the signs to Xinzhuang Stadium, as the Baseball Stadium is located next door and can be easily found.
There is a station located at 4 Xinzhuang station, Exit 1. Taking a Youbike is recommended, as there is also a station directly outside the main gate of the stadium.