The present invention relates to the method and the apparatus for converting cylinder shaped bamboo culms into flat, solid bamboo sheets that can be further processed into various high value-added products. The culm internodes are cut in a series of V-shaped grooves at its outer-side by a special design grooving machine at a predetermined grooving interval. The optimum grooving intervals, which are the function of culm diameter, thickness and the grooving angle, are tabulated in a Grooving Table for simple operator use. Each grooving has 0.5-1.0mm depth grooving cease that serves as pivoted connector to maintain the culm intact and provides pivoted hinge function necessary for flattening process. After series of grooving being completed and the last groove is cut through, the grooved culm is opened up by hand and simply flattened under a pressing machine or clamper. The hinge function of the grooving cease transfers the vertical forces of the pressing into lateral forces that facilitate each the groove to close tightly and can be fixed become flat sheet upon they has been previously coated with certain glue. Since the flattened culm is wide and laterally straight, it can be efficiently and practically planed by a planing machine on one or both of its surfaces and then used for producing of laminated bamboo boards or planks. The advantage is that the processing steps are shorter and more efficient as compared to the conventional split-and-squaring method. Therefore, the product production cost with this method is expected to be lower than those of the conventional method. On top of that, as the machine used is small and relatively simple in its construction, this method and apparatus will be suitable for medium- and small-scales bamboo processors, especially those from bamboo producing countries such as in Malaysia, Indonesia, India, China, Thailand, and Philippines.