The wand of Cho Chang is of unknown length, wood, and core. Like most wizards and witches in Great Britain, she likely purchased it at the age of eleven from Ollivander before beginning her education at Hogwarts School of Witchcraft and Wizardry in 1990. She performed a wide range of powerful magic with the wand, from charms to defence. During her training with Dumbledore's Army, Cho also learned to produce a fully corporeal Patronus, a feat which Remus Lupin mentioned to be quite impressive for young wizards.
Cho Chang casting a spell with Harry Potter's help.