Hg1-xCdxSe are II-VI semiconductors alloys with optoelectronic properties that depend upon the molar fraction x, which can be further controlled by nanostructuring. In this work one electron confined in a zero-dimensional lens-shaped nanostructure of Hg1-xCdxSe surrounded by a matrix of different molar fraction is analyzed and its electronic properties are studied under external magnetic and electric fields. Our system was modeled by means of the 3D Schrodinger equation in the framework of the effective mass approximation, which was solved using a finite element method. The model is described by a discontinuous space with Ben Daniel-Duke boundary conditions. We calculated the energy spectrum and the corresponding probability density of the electron for some low-lying energy levels as a function of: electric field strength on plane and magnetic field strength applied along the growth direction. Also, the effect of finite confinement potential was studied in presence of a uniform magnetic field. Our results shown that the electronic properties of Hg1-xCdxSe quantum dots are highly sensitive to a threading magnetic field because the degenerate energy levels are split. On the other hand, the effect of electric and magnetic fields applied simultaneously on a quantum dot can increase the system stability against external perturbation, e.g. thermal interactions.