Highly dynamic solar eruptive activities occurring over the corona and transition region triggered by magnetic field reconnection are the driving source of disastrous space weather, and space imaging and spectroscopic measurements of solar eruptive activities are a key data source for accurate space weather forecasting. The He II 30.4 nm resonance line is the Lyman <i>α</i> transition of singly ionized helium, which has an anomalous intensity with enhancement of up to an order of magnitude relative to the intensities of other transition region lines. In this paper, we innovatively propose and design a two-dimensional spectroscopy tomographic imaging instrument operating at He II 30.4 nm wavelength to address the shortcomings of conventional solar extreme ultraviolet imagers and imaging spectrometers, and adopt a slitless three-order (-1, 0, +1) simultaneous diffraction imaging configuration with a single snapshot to achieve two-dimensional spectroscopy instantaneous imaging with a large field of view. Due to the confusion of spatial and spectral information of the three orders of images, the 3D data cube <i>I (x, y, λ)</i> of the observed target is reconstructed using a spectral data inversion algorithm with a limited tomographic projection angle.