Objective To investigate the appropriate dose of carboplatin and ultrasonic energy parameters for ultrasound assisting carboplatin on A549 cell line in vitro. Methods A549 cells were plated in 96-well plates, and carboplatin was added in a concentration gradient of 0-400μg/ml for 24 hours. Then 10μl CCK-8 was added to each well and cells were incubated for 1.5 hours. The absorbance at 450 nm was measured to calculate the cell inhibition rate. The IC50 of carboplatin for 24-hour was calculated using the Graphpad Prism 5 software with drug dose-effect model. Blank group, US group, USMB group, CBP group, CBP+US group, CBP+USMB group were set under condition of 50 μg/ml carboplatin, low intensity gradient range of untrasound from 0.2 to 2.2W/cm2, US frequency =1MHz; duty cycle =10%, sonication time=1 minute. After 24 hours, cell viability was measured by CCK8 assay. Differences of survival rates were analyzed using SPSS24.0, and appropriate dose range was discovered. Optical inverted microscope was used to observe the morphological changes of cells in each group. Results The IC50 of carboplatin for 24 hours was 65.72μg/ml. The inhibitory effect was ranked as CBP+USMB group>CBP+US group>CBP group>USMB group>US group, the difference was significant (P<0.001). However, no significant difference was found among the five CBP(50μg/ml)+USMB(0.2-1.0W/cm2) groups(P>0.05). In the treatment groups, some cells were in irregular shape and adherence was reduced, which was most significant in the CBP+USMB group. Conclusion 50μg/ml carboplatin and intensity 0.6W/cm2 are the appropriate dose for CBP+USMB therapy for A549 Cell line in vitro. Ultrasound combined with microbubbles can assist carboplatin and inhibit the viability of A549 cells. It may become a new strategy for cancer therapy.