B-physics results from Dط

A number of B-physics results from the DØ experiment at the Fermilab Tevatron Collider are reported. Measurements of bb̄ production in pp̄ interactions at s=1800 and 630 GeV are used to evaluate, for the first time with the same detector, the center-of-mass energy and rapidity dependence of b-quark production cross section. A measurement of the bb̄ angular correlations using dimuon triggers is also presented. Preliminary results from these measurements are compared with the next-to-leading order QCD predictions. Finally, dimuon data samples are used to study pT and rapidity dependence of b-produced and direct charmonium productions.