Provide is a ray dose detection device adaptable for coupling with a terminal and a method for detecting a ray dose, which relate to a field of an environmental detection technology. The device includes: a housing (1), a scintillator (2) and a light shielding layer (3). The housing (1) has an accommodating space (11) and a window (12), the accommodating space (11) is connected with the window (12); the scintillator (2) is configured to receive a ray and convert the received ray to a visible light, the scintillator (2) is located in the accommodating space (11), the scintillator (2) covers the window (12), an outer surface of the scintillator (2) includes a first outer surface and a second outer surface, and the first outer surface is adapted to a camera of the terminal; and the light shielding layer (3) is configured to shield the scintillator (2) from a visible light in an external environment, the light shielding layer (3) is arranged on the second outer surface of the scintillator (2), wherein the ray dose detection device is mountable on the terminal to enable the scintillator (2) and the window (12) to face the camera of the terminal, so as to convert the ray in the external environment to the visible light suitable for being received by the camera of the terminal.