Abstract. With the discovery of gravitational waves from merging pairs of massive black holes, the interest in the question whether Primordial Black Holes (PBHs) could constitute the Dark Matter (DM) has recently been revived. In this talk, I will review the different mechanisms for (DM) PBHs formation with special focus on inflation which can source the required large density fluctuations for PBHs formation. I will explain in detail the possibility of DM PBHs formation by particle production during inflation. I will consider the scalar and the gauge quanta production in inflation models. In a model independent way I will show that the non-production of DM PBHs puts stronger upper bound on the particle production parameter. In the scenario where the inflaton field coupled to a scalar field, one can put an upper bound on the amplitude of the generated scalar power spectrum by non-production of PBHs.