Absolute non-resonant recombination (RR) rate coefficients of Ni19+ ions were measured by employing the electron-ion merged-beams technique at the main cooler storage ring in Lanzhou. Using the electron cooler and energy detuning system, we obtained a narrow momentum spread (Delta p/p similar to 2 x 10(-4))and tuned precisely relative energies (minimum electron energy detuning step voltage 1 V) between electrons and ions. In addition, we compared the RR rate coefficients with the theoretical ones calculated by the self-consistent-field Dirac-Slater method, and found that they are in good agreement.