Background: Despite that AC-THP regimen is one of the commonly used regimens for neoadjuvant treatment of HER2-positive breast cancer, previous studies showed that pCR rate rarely exceeds 70%. We hypothesized that prolonged dual anti-HER2 therapy can increase pCR rate in neoadjuvant therapy. In this study, we designed a single-arm trial of ACHP-THP regimen (continuous dual anti-HER2 therapy of trastuzumab and pertuzumab) in neoadjuvant therapy of HER2 positive breast cancer. To minimize adverse cardiovascular events, we used pegylated liposomal doxorubicin (PLD) and Nab-Paclitaxel (Nab-P) instead of doxorubicin and paclitaxel. We aimed to examine whether continuous dual anti-HER2 therapy can boost pCR rate in the neoadjuvant therapy. The cardiotoxicity was closely monitored when the anti-HER2 therapy was combined with PLD and Nab-P respectively. Methods: Upon approval by the Medical Ethics Committee of Xijing Hospital, patients with HER2-positive breast cancer (cT2-3/N0-1/M0) receiving neoadjuvant therapy, were enrolled. The patients were treated with PldCHP (pegylated liposomal doxorubicin 35mg/m², cyclophosphamide 600mg/m², trastuzumab 8 mg/kg loading, then 6 mg/kg, pertuzumab 840 mg loading, then 420 mg, iv, q3w) for 4 cycles followed by Nab-PHP (Nab-Paclitaxel 260mg/m², trastuzumab 6 mg/kg, pertuzumab 420 mg, iv, q3w) for 4 cycles, with strict monitoring of cardiotoxicity. The primary endpoint was pCR rate, and secondary endpoint was cardiotoxicity during neoadjuvant therapy. Results: From January 2020 to October 2021, a total of 96 patients were recruited. Among the 96 patients with a median age of 49 (21-71), 58 patients were HR positive and 42 patients had positive lymph node status. Overall, the pCR rate was 80.2% (77/96). The ER-positive tumor achieved a higher pCR rate than ER-negative tumor (82.8% vs 76.3%, p=0.439), but the difference was statistically insignificant. Multivariate regression analysis showed that for participants older than 30, HER2 3+ (IHC) showed a statistically significant positive influence on pCR rate. The common adverse reactions of grade ≥3 were neutropenia (30.2%), asthenia (8.3%), and peripheral sensory neuropathy (7.3%). Left ventricular insufficiency was detected in 4 patients, and no cardiotoxic events higher than grade 2 occurred during the neoadjuvant therapy. There was no treatment-related death. Conclusions: The PldCHP---Nab-PHP regimen is a feasible and effective neoadjuvant therapy for early stage HER2-positive breast cancer, showing high pCR rate and acceptable cardiotoxicity. These results support a further random controlled trial testing for continuous dual anti-HER2 therapy combined with PLD in neoadjuvant or adjuvant therapy of HER2 positive breast cancer.