The Swift Deep Galactic Plane Survey is a Swift Key Project consisting of 380 tiled pointings covering 40 sq. deg of the Galactic Plane between longitude 10<|l|<30 deg and latitude |b|<0.5 deg. Each pointing has a 5ks exposure, yielding a total of 1.9Ms spread across the entire survey footprint. Phase-I observations were carried out between March 2017 and May 2021. The Survey is complete to depth >1*10^34^erg/s to the edge of the Galaxy. The main Survey goal is to produce a rich sample of new X-ray sources and transients, while also covering a broad discovery space. Here, we introduce the Survey strategy and present a catalog of sources detected during Phase-I observations. In total, we identify 928 X-ray sources, of which 348 are unique to our X-ray catalog. We report on the characteristics of sources in our catalog and highlight sources newly classified and published by the DGPS team.