To effectively improve the strength of Plectocomia pierreana rattan cane without reducing its toughness, the cane was impregnated with a new water-soluble melamine-urea-formaldehyde (MUF) resin modified with low-molecular-weight polyethylene glycol (PEG), marked as PMUF. The PMUF synthetic process was optimized using an orthogonal test L9(34). Results showed that the dimensional stability, density, and most mechanical properties of modified canes were improved greatly. Compared with MUF, PMUF imparted the cane with higher anti-swelling efficiency (ASE), modulus of elasticity (MOE), modulus of rupture (MOR), and impact toughness. These improvements indicated that PMUF could effectively improve the cane’s dimensional stability and strength, while simultaneously retaining its flexibility. Based on a comprehensive evaluation, the optimum modification conditions were: PEG-400, PEG/Melamine mole ratio of 0.1, step-wise synthesis, and PMUF solution of 30%. The ASE of optimal modified canes reached 65.51%, and its mechanical properties such as the MOE, MOR, compressive modulus, and compressive strength increased by 135.61%, 129.01%, 106.22%, and 88.52%, respectively. Additionally, its impact toughness was only reduced by 6.85%. The PMUF modified P. pierreana canes is comparable to the commercial Daemonorops margaritae canes.