Create .ui in QT Designer (QT Creator > New File > QT Form)
import sys
from PyQt4.QtGui import QApplication, QDialog
from PyQt4 import uic
app = QApplication(sys.argv)
# returns a QWidget subclass
# assume that dialog.ui is created from QT designer
ui = uic.loadUi("dialog.ui")
ui.show()
sys.exit(app.exec_())