An outdoor temperature-controllable photo-bioreactor system for algae is provided and includes a closed bioreactor tube immersed in a temperature-controllable reservoir disposed in an outdoor environment for directly using sunlight as a light source and simultaneously using temperature-controllable water in the temperature-controllable reservoir to control the temperature of the bioreactor tube within a suitable temperature range, so as to provide a better environmental conditions for algae growth. Moreover, the shading net and/or the water depth of the reservoir can be adjusted to provide an appropriate sunlight transmittance, so as to precisely control the illumination intensity for the bioreactor tube.一種室外溫控微藻光生物反應系統,其係將一封閉式之光反應管沈浸在一溫控水槽內,並將整組系統設置於一室外環境,以利用室外太陽光做為光源,及同時利用該溫控水槽內之溫控水對該光反應管進行恆溫調控,因而可提供適合微藻生長的較佳環境條件。再者,亦可藉由調整至少一遮光網的透光率及/或改變該溫控水槽之水深,以提供適當之太陽光遮蔽率,進而精確調控對該光反應管之光照強度。1...溫控水槽11...溫控水入口111...閥體12...溫控水出口121...閥體2...光反應管21...透光管體22...快拆接頭23...藻水入口231...閥體24...藻水出口241...閥體3...循環蓄養槽31...灑水頭32...打氣裝置33...排氣管34...注水口35...檢測窗口36...藻水溫度調節器4...循環泵41...藻水回收控制閥5...遮光網51...捲動裝置