Dependability analysis is the main method to evaluate the design of safety-critical systems, which is able to analyze the source of the faults and find them as early as possible. With the increasing system scale and complexity, Model-Based Dependability Analysis (MDBA) has become the mainstream, so that it is crucial to provide powerful models that accurately reflect the real systems and easy to be built. However, modeling a system is error-prone and it is difficult to verify the correctness of the model being built. Therefore, this paper proposes our dependability modeling tool called DATAM (Dependability Analysis Tool of AltaRica Model), which is based on AltaRica, a dataFlow language. We present a method for converting key elements of AltaRica into model/GUI components, thereby ensuring the consistency of the model with the modeling language. GUI-based operations and rich custom components ensure ease of using DATAM. Besides, some components of the model can be edited directly through the AltaRica script and can be interchanged with GUI components. Finally, DATAM supplies varieties of reliability calculation functions. We demonstrate the ability of DATAM through a case study and compare the results with SimFia education version.