A floating-type milling and flattening apparatus for arc-shaped bamboo sheets, which is used for flattening softened arc-shaped bamboo sheets. The apparatus comprises a conveying and feeding mechanism (200) and a bamboo sheet processing mechanism (100) that are electrically connected to a control system. A feeding end of the conveying and feeding mechanism (200) is provided with a sensor assembly (210) which detects the thickness of bamboo sheets in real time. The bamboo sheet processing mechanism (100) comprises a frame (10), and a shaping mechanism, milling mechanism and flattening mechanism that are sequentially arranged on the frame (10), and processing surfaces of the shaping mechanism, milling mechanism and flattening mechanism are located on the same horizontal plane. The shaping mechanism comprises multiple groups of shaping roller assemblies (20) which are arranged in parallel and which have radii that gradually increase. The milling mechanism comprises a floating de-yellowing milling assembly (30), a de-greening milling assembly (40), and a conveying roller assembly (50) disposed between the two. The flattening mechanism comprises multiple groups of flattening roller assemblies (60) which are arranged in parallel and which have radii and/or flatness degrees that gradually increase, and at least one group of pressing roller assemblies (70), and the pressing roller assemblies (70) are located at the output end of the flattening roller assemblies (60). The apparatus has a compact structure and precise control, may continuously mill and flatten arc-shaped bamboo sheets of different thicknesses and reduce the amount of bamboo cutting, and has good practicability.