Atmospheric　particulate　matter　(PM)　was　measured　continuously　at　an　urban　site　in　Baoji　city　in　northern　China　in　2018　to　investigate　the　seasonal　distribution　characteristics.　Coarse　PM　(PM2.5-10)　was　more　prevalent　in　spring,　substantially　due　to　the　regional　transport　of　dust.　High　loadings　of　coarse　PM　were　found　at　night　compared　to　daytime,　which　could　result　from　high　production　and　unfavorable　dispersion　conditions.　Fine　PM　(PM2.5)　constituted,　on　average,　54%　of　the　total　PM　mass　concentration,　whereas　it　contributed　more　than　97%　of　the　total　PM　number　concentration.　The　number　and　mass　concentrations　of　fine　PM　increased　substantially　in　the　winter,　which　was　possibly　due　to　the　enhanced　production　of　atmospheric　secondary　processes　and　coal　combustion.　Precursor　gaseous　pollutants　and　meteorology　greatly　influenced　the　PM　distributions.　Fine　PM　was　associated　more　strongly　with　gas　pollutants　than　coarse　PM,　which　suggested　that　it　largely　originated　from　secondary　production　and　combustion　sources.　High　relative　humidity　appeared　to　promote　the　production　of　fine　PM,　whereas　it　facilitated　the　removal　of　coarse　PM.　This　study　highlights　that　different　air-pollution　control　strategies　should　be　used　for　coarse　and　fine　PM　according　to　the　distribution　characteristics　and　influencing　factors　in　similar　medium-sized　urban　areas.