The Catholic Church cannot be said to be "Arminian" because it came before Arminianism and is not a product of that theology. Rather, it is better to say that Calvinism and Arminianism agree with Catholicism on some issues and disagree with it on others.
Calvinism was formulated by John Calvin in the sixteenth century. Calvin, in his Institutes of the Christian Religion, wove together a systematic theology that eventually would be remembered by the acronym TULIP. TULIP stands for total depravity, unconditional election, limited atonement, irresistible grace, and perseverance of the saints.
Arminianism, named for its principal theologian, Jacobus Arminius, can be distilled to the five points it made that provoked a reaction from Calvinists, known as the Five Articles of the Remonstrants: apart from grace man cannot save himself or do anything truly good, conditional election, unlimited atonement, resistible grace, and the possibility of apostasy. (The first of these converges with Calvinism’s understanding of total depravity, though later Arminians and Calvinists have developed this idea differently.)
In some respects Catholicism and Calvinism agree (e.g., Catholic theologians from Thomas Aquinas to Robert Bellarmine have taught unconditional election) and in some they disagree (the Church does not teach that all believers are predestined to persevere in the faith). In some respects Catholicism and Arminianism agree (the Church teaches universal redemption) and in some they can disagree (the Church allows for the possibility of unconditional election).