An optical touch device and a touch detecting method using the same are provided. The optical touch device is suitable for use with a touch surface and includes a control unit and first to fourth optical capturing units. The first to fourth optical capturing units are disposed on a side of the optical touch device close to the touch surface. The first to fourth optical capturing units are respectively disposed at predetermined distances from the touch surface and are disposed based on predetermined angles. A touch covering area of each of the first to fourth optical capturing units is obtained respectively based on the predetermined distance and the predetermined angle. The touch covering area is positively correlated to the predetermined distance. At least one touch point on the touch surface is calculated by the control unit based on optical sensing information captured by the first to fourth optical capturing units.