The purpose of this study was to develop the Process-Oriented Diagnostic Assessment Battery (PODAB) for single-step word problem of addition and subtraction through componential and content analyses. Participants were composed of 477 first graders from Chiayi by convenient and cluster sampling. Participants were administered the PODAB. Item analysis suggested good passing percentage, internal correlation and critical ratio, regardless whether in single items, sub-battery or the whole battery. As for construct validity, three factors were suggested by exploratory factor analysis and confirmatory factor analysis (basic solving, quantity identification, and checking skills), and there were appropriate dimentionality, variance proportions of factor extraction, model fit, as well as criterion-related and predictive validity. For reliability, results showed appropriate internal consistency coefficient and composite reliability. Finally, because of individualized information, the battery could provide diagnostic profile and subsequent prescriptions.