In 1913 Kralj studied sculpture in Vienna, Austria. In 1915 he stopped his studies because of the start of World War I. In 1919 he studied in Prague, Czech Republic for two years. For many years he was a professor at the Ljubljana Secondary Technical School. In 1933 his autobiography "Moja pot" (My way) was published. In 1937 he won a prize at the world exhibition in Paris for his sculpture "Zrebe" (Foal).