There is a good explanation on this post regarding this. There are no guarantees that the AlarmClock app will be on every device your app is installed on. For example, many of the HTC phones replace it with HTC's own "World Clock" app.
However, assuming the stock AlarmClock app is present, you should be able to get a cursor from its content provider. See this project as an example.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
