A new visual fluorescent probe based on carbon nano-dots (CNDs) has been facilely synthesized via one step microwave-assisted pyrolysis and utilized for sequential detection of arginine (Arg) and Cu2+ by fluorescent and colorimetric dual-readout assay. The fluorescence of CNDs can be effectively quenched by Arg, and recovered upon addition of Cu2+ due to the competitive binding of Arg and Cu2+ that leads Arg to escape from the surface of CNDs. The probe displayed high sensitivity and selectivity toward Arg and Cu2+ over other analytes with a low detection limit of 0.26 μM and 0.17 μM, respectively. Meanwhile, the CNDs can also give dual responsive signals of a visible color change (yellow-pink-light yellow). According to this phenomenon, an "AND" logic gate based on the novel CNDs has been constructed. More importantly, the probe was also extended to cellular imaging. The proposed method was simple with ease of operation, which demonstrated great potential in bio-sensing, disease diagnosis or environmental monitoring.