In this paper, we propose graphene-based plasmonic multimode interference power splitters with ultra-compact size working in mid infrared range. Further, the arbitrary-ratio 1×2 power splitter with a size of 140 nm×232 nm, where the splitting ratio can be tuned continuously from 1:1 to 100:0, is numerically demonstrated. Meanwhile, the graphene-based arbitrary-ratio 1×2 power splitters with different frequencies and chemical potentials are also investigated. The proposed multimode interference structure with a deep nanoscale footprint might be a fundamental component of the future high density integrated plasmonic circuit or on-chip plasmonic interconnect techniques. In this paper, we propose graphene-based plasmonic multimode interference power splitters with ultra-compact size working in mid infrared range. Further, the arbitrary-ratio 1 × 2 power splitter with a size of 140 nm × 232 nm, where the splitting ratio can be tuned continuously from 1: 1 to 100: 0, is numerically demonstrated. Meanwhile, the graphene-based arbitrary-ratio 1 × 2 power splitters with different frequencies and chemical potentials are also investigated. The proposed multimode interference structure with a deep nanoscale footprint might be a fundamental component of the future high density integrated plasmonic circuit or on-chip plasmonic interconnect techniques.