In this research, carbon dots were prepared by a new method using pine tree needles, which showed many advantages such as high fluorescence intensity, good solubility in water and appropriate stability. Characterization of these carbon dots was done by XRD, EDX, TEM, FT-IR, TGA and DLS techniques as well as Zeta potential measurements. Also, their stability and optical properties were investigated in different experimental conditions. The carbon dots produced by this method were used to preparation of chromium doped zinc oxide-carbon dots nanocomposite (Cr-ZnO/CDs). The characterization of the synthesized nanocomposite was also accomplished by FT-IR, FE-SEM, XRD and EDX techniques. Then, the ability of this nanocomposite to reduce and remove the concentration of Amido Black 10B dye (usage of various industries, such as the textile industry) was investigated using synergetic effect of two phenomena including adsorption and photocatalytic effects. Various experiments were carried out in the presence or absence of light for removal of the Amido Black 10B dye by the nanocomposite. Finally, the experimental variables were optimized for the removal of Amido Black 10B dye by using synthetic nanocomposite. Under the optimal experimental conditions, about 95% of the concentration of Amido Black 10B dye in the absence of light and in less than 15 min was removed by the nanocomposite. The simultaneous usage of the adsorption and photocatalysis phenomena (under simulated sunlight) also, resulted in the removal of about 99% of this color in less than 15 min by the nanocomposite.