With over 3 billion UnionPay cards issued worldwide, discover the largest and fastest growing card scheme The second largest card network in the world, UnionPay is also the only network in China. By far the most popular card payment method in the country, this household name has more than 250 bank members in China and worldwide. UnionPay cards can be used in more than 140 countries and regions: it is the payment method of choice for Chinese shoppers buying abroad.