Salvia miltiorrhiza Bunge is a traditional Chinese medicinal herb widely used to treat cardiovascular and cerebrovascular diseases at clinic. Its main water-soluble components are rosmarinic acid (RA) and salvianolic acid B (SAB), which are produced by phenylpropanoid pathway. 4-Hydroxyphenylpyruvate reductase (HPPR) is a key enzyme in phenylpropanoid metabolism pathway. SmHPPR1 was cloned from S. miltiorrhiza and was constructed into plant expression vector pJR-SmHPPR1. On this basis, SmHPPR1 transgenic Arabidopsis plants were induced and the content of 4-hydroxyphenyllactic acid (pHPL) was determined. SmHPPR1-overexpressing (SmHPPR1-OE) hairy roots of S. miltiorrhiza were obtained and the concentration of active components and transcriptome analysis were performed. The results showed that the concentration of pHPL in SmHPPR1 transgenic Arabidopsis T1 was 0.594 mg·g^-1 dry weight. The concentration of RA, SAB and total salvianolic acid in SmHPPR1-OE-3 hairy roots were 1.09, 1.29, 1.15 times of that in control-3, respectively, and the content of Danshensu was 36.26% of that in control-3. Transcriptomic analysis revealed that overexpression of SmHPPR1 caused the upregulation of other phenylpropanoid pathway genes like SmTAT2. Protein-protein interaction indicated CYT (TR74706_c0_g1), NADP⁺ (TR26565_c0_g1) and NADP⁺ (TR68771_c0_g1) is the central node of the network and participated in metabolic process and cellular process. The tracking work in this study proved that SmHPPR1 could catalyze the reduction of 4-hydroxyphenylpyruvic acid to 4-hydroxyphenyllactic acid in SmHPPR1 transgenic Arabidopsis, and SmHPPR1-overexpressing in hairy roots of S. miltiorrhiza could increase the concentration of salvianolic acids through synergistically regulating other pathway genes.