目前煙囪及囪底隧道興建於西元1939(昭和14)年，由大日本製糖株式會社所建，位於鍋爐室後方，為糖廠歷經西元1935(昭和10)年關刀山大地震後將原位於如今修護所後方原址遷移至現址後重新建造。煙囪原基座直徑4.5公尺，頂部直徑3公尺，地面高53公尺，基礎深度3.5公尺，總高56.5公尺，歷經第二次世界大戰盟軍轟炸過。停產後因安全顧慮將部分煙囪截斷，現況總高僅剩約34公尺。煙道以耐火磚砌築拱形隧道，連接鍋爐及煙囪將廢氣排除。

綜觀台灣目前各製糖工場，月眉糖廠製糖工場之煙道為全台製糖工場中，唯一完整保留之煙道設施。煙道兩側側牆距離地面約1.3公尺處砌有兩塊交錯之紅磚凸出於牆面且呈兩兩對稱，間隔約1公尺。據退休員工轉述，早期有4座鍋爐，當時因為有時候，不需要4座鍋爐全部啟用燃燒。故會以鐵製隔板靠在兩凸出的紅磚前，縮短煙道距離，以節省燃料。

The chimney and under-chimney tunnel located behind the boiler room was established in 1939 by Dai-Nippon Seitou K.K.. The tunnel originally located behind repair room has been moved and reconstructed here after Kuantaoshan-earthquake in 1935. The diameter of the chimney throat and top were 4.5 m and 3m. The height of the chimney were 53m above ground and 3.5m below, total height was 56.5m. Due to safety considerations, the tunnel was truncated from to 34m after World War II. Yuehmei Sugar Refinery also features the under-chimney tunnel originally built as an arch-shaped smoke ventilation tunnel with bricks, which was made for expelling the smoke produced by the boilers.

Also, Yuehmei Sugar Refinery has an under-chimney tunnel that could be found nowhere else in Taiwan. Two bricks about 1.3m above ground, projected from the side wall of the tunnel were formed symmetrically and kept 1m apart. According to retiree, Yuehmei Sugar Refinery contained 4 boilers, some of them would be separated by iron plate to shorten the distance of the tunnel to save fuel.

使用Gmap查詢：

1.  國道一號南下北上由中山高速公路160km==>交流道出口==>甲后路==>月眉觀光糖廠
2. 中二高(國道三號)北上或南下在大甲下交流道,往東約5分鐘即可抵達月眉觀光糖廠

1. 北上（由豐原往后里）：三豐路（左轉）→甲后路→月眉觀光糖廠 
2. 南下（由苗栗往后里）：三豐路（右轉）→甲后路→月眉觀光糖廠 
3. 海線（由大甲往后里）：西濱快速公路→甲后路→月眉觀光糖廠