Dust grain surface potential is presented in a non-Maxwellian dusty plasma, whose constituents are the electrons, as well as the positive/negative ions and negatively charged dust grains. For this purpose, we have solved the current balance equation for a negatively charged dust grain to attain a steady state value (viz. q_d=constant) in the presence of power-law -distribution. In fact, the current balance equation becomes modified due to two types of negative ion distributions. These are the streaming negative ions and the Boltzmannian distributed negative ions.The relevance of present results to low-temperature laboratory plasmas in the presence of negative ion distributions is discussed in this context when the plasma particles are far away from the thermal equilibrium.