The invention discloses a polyamide resin A which has a relative viscosity of 1.2-1.8 in 98% concentrated sulfuric acid at 25 DEG C; the polyamide resin A has an amino end group value of 20-60 mol/t, and a carboxyl end group value of 70-130 mol/t; in the polyamide resin A, the proportion of benzoic acid in repetitive units is 2-6 mol%; the polyamide resin A is polymerized by adding polyfunctional compounds during the polymerization process; the adding amount of the polyfunctional compounds is 0.1-1 mol%. The polyamide composition comprises the following components: 31-99 wt% of polyamide resin A; 0-68 wt% of polyamide resin B; 0.8-40 wt% of mineral fillers; and 0.2-1 wt% of other additives. The polyamide resin A of the invention has low apparent viscosity under fusion conditions, has high fluidity; when a certain ratio of polyamide resin A is added into semi-aromatic polyamide, the prepared polyamide composition has high fluidity and comparable mechanical properties, and is applicable to conditions with high injection molding product dimension requirements.