The invention discloses castable and forgeable solid solution tungsten alloy and a preparation method, and belongs to the technical field of refractory alloy. According to the chemical components, thecastable and forgeable solid solution tungsten alloy comprises, by weight percentage, 20%-75% of W, 0%-20% of Mo, 0%-20% of Nb, 0%-20% of Ta, 0%-10% of Hf, 0%-10% of V, 0%-10% of Zr, 0%-10% of Ti, 0%-10% of Al, 0%-5% of Cu and the balance Ni or Co and inevitable impurity elements and microelements, specifically, the Ni element and the Co element can be partially replaced by one or two or more elements of 0%-50% of Ir, 0%-30% of Fe, 0%-20% of Cr, 0%-20% of Re and 0%-20% of Ru. The castable and forgeable solid solution tungsten alloy further comprises the following one or two or more grain boundary strengthening elements of 0.001%-1.0% of C, 0.001%-1.0% of B, 0.001%-1.0% of Y, 0.001%-1.0% of La or Ce or the rare earth element, 0.001%-1.0% of Mg and 0.001%-1.0% of Ca. The castable and forgeable solid solution tungsten alloy has the advantages of being high in density, ultrahigh in strength, high in toughness and high in hot-working performance. The alloy is castable and forgeable and canbe formed through 3D printing, the density ranges from 11.0g/cm<3> to 15.0g/cm<3>, the impact toughness is 80J/cm<2> or above, and the tensile strength is 1700MPa or above.